JP7082958B2 - Electrochemical reaction cell stack - Google Patents

Description

The techniques disclosed herein relate to electrochemical reaction cell stacks.

A solid oxide fuel cell (hereinafter referred to as "SOFC") having an electrolyte layer containing a solid oxide is known as one of the types of fuel cells that generate power by utilizing an electrochemical reaction between hydrogen and oxygen. Has been done. A fuel cell single cell (hereinafter, simply referred to as “single cell”), which is a constituent unit of SOFC, has an electrolyte layer and air that faces each other in a predetermined direction (hereinafter, referred to as “first direction”) across the electrolyte layer. Includes poles and fuel poles.

SOFCs are generally used in the form of fuel cell stacks comprising electrochemical reaction blocks in which a plurality of electrochemical reaction units are arranged side by side in a first direction. The electrochemical reaction unit includes, for example, a single cell, a frame member, and a separator. The frame member is formed with a through hole constituting an air chamber facing the air electrode or a fuel chamber facing the fuel electrode. In the separator, a through hole is formed, a through hole peripheral portion surrounding the through hole is joined to a single cell, and a peripheral edge portion is joined to a frame member to separate an air chamber and a fuel chamber. The fuel cell stack further comprises a pair of end members located on either side of the electrochemical reaction block in the first direction, respectively, and arranged so that at least a part of the fuel cell stack overlaps the frame member in the first direction view (eg,). , Patent Document 1).

Japanese Unexamined Patent Publication No. 2017-10709

By the way, in the above-mentioned fuel cell stack, it is conceivable that a space is formed in at least one of the pair of end members. The space formed in this end member is open at least toward the electrochemical reaction block side, and the contour line of the space encloses a single cell in the first directional view. In the electrochemical reaction cell stack in which the space is formed in the end member in this way, for example, the space is not formed in the end member, and the entire surface of the end member on the electrochemical reaction block side is flat as compared with the configuration. Due to the fact that the loads received from the pair of end members of the frame member and the single cell in the electrochemical reaction block are different from each other, a displacement difference between the frame member and the single cell is likely to occur in the first direction. Then, for example, the displacement difference between the frame member and the single cell in the first direction becomes larger due to a thermal cycle, a heat shock, or the like. When a displacement difference between the frame member and the single cell occurs in the first direction, for example, a force that pulls the single cell in the first direction via a separator causes a crack in the single cell, or the frame member. There is a problem that the performance of the electrochemical reaction cell stack is deteriorated, such as deterioration of the sealing property due to the above.

In addition, such a problem is an electrolytic cell including a plurality of electrolytic cells which are constituent units of a solid oxide type electrolytic cell (hereinafter referred to as "SOEC") that generates hydrogen by utilizing the electrolysis reaction of water. It is also a common issue for stacks. In the present specification, the fuel cell single cell and the electrolytic single cell are collectively referred to as an electrochemical reaction single cell, and the fuel cell stack and the electrolytic cell stack are collectively referred to as an electrochemical reaction cell stack. Further, such a problem is common not only to SOFC and SOEC but also to other types of electrochemical reaction cell stacks.

This specification discloses a technique capable of solving the above-mentioned problems.

The techniques disclosed herein can be realized, for example, in the following forms.

(1) The electrochemical reaction cell stack disclosed in the present specification includes a single cell including an electrolyte layer and an air electrode and a fuel electrode facing each other in a first direction with the electrolyte layer interposed therebetween, and the air electrode. A frame member having a frame through hole forming a facing air chamber or a fuel chamber facing the fuel electrode, and a separator through hole are formed, and a through hole peripheral portion surrounding the separator through hole is joined to the single cell. A plurality of electrochemical reaction units having a peripheral portion joined to the frame member and a separator separating the air chamber and the fuel chamber are arranged side by side in the first direction. And a pair of end members located on both sides of the electrochemical reaction block in the first direction and arranged so that at least a part thereof overlaps the frame member in the first direction view. In the chemical reaction cell stack, at least one of the pair of end members is a space that is open to at least the electrochemical reaction block side, and the contour line includes the single cell in the first direction view. The at least one separator is formed to connect an inner portion including the peripheral portion of the through hole, an outer portion located on the outer peripheral side of the inner portion, and the inner portion and the outer portion. A connecting portion that projects to one side in the first direction with respect to both the inner portion and the outer portion is provided.

In this electrochemical reaction cell stack, a space is formed in at least one of the pair of end members. This space is open at least on the side of the electrochemical reaction block, and the contour line encloses a single cell in the first directional view, which is the direction in which the plurality of electrochemical reaction units are arranged. In the electrochemical reaction cell stack in which the space is formed in the end member in this way, for example, the space is not formed in the end member, and the entire surface of the end member on the electrochemical reaction block side is flat as compared with the configuration. In the electrochemical reaction block, the frame member and the single cell are likely to have a displacement difference in the first direction between the frame member and the single cell due to the different loads received from the pair of end members. Then, for example, the displacement difference between the frame member and the single cell in the first direction becomes larger due to a thermal cycle, a heat shock, or the like. When a displacement difference between the frame member and the single cell occurs in the first direction, for example, the single cell is pulled in the first direction via a separator, so that the single cell is cracked or sealed by the frame member. There is a risk that the performance of the electrochemical reaction cell stack will deteriorate, such as deterioration of the properties. On the other hand, according to this electrochemical reaction cell stack, the connecting portion of the separator functions like a spring that easily expands and contracts, and the separator is easily deformed at the position of the connecting portion. When the displacement difference in the first direction becomes large, the separator is deformed so as to extend mainly at the position of the connecting portion, and as a result, the stress generated in the single cell or the frame member due to the displacement difference is relaxed, so that the frame member It is possible to suppress the deterioration of the performance of the electrochemical reaction cell stack due to the displacement difference between the cell and the single cell in the first direction.

(2) In the electrochemical reaction cell stack, in at least one cross section parallel to the first direction, the first direction of the single cell and the frame member joined to the at least one separator. The first distance, which is the distance in the third direction orthogonal to the single cell, is the cell-side joining portion joined to the single cell and the frame side joined to the frame member in the at least one separator. The configuration may be longer than the second distance, which is the distance to the joint in the first direction.

In the present electrochemical reaction cell stack, in at least one cross section parallel to the first direction, the distance between the single cell joined to the at least one separator and the frame member in the third direction orthogonal to the first direction. The first distance is the distance in the first direction between the cell-side joint portion joined to the single cell and the frame-side joint portion joined to the frame member in the at least one separator. Longer than the second distance. Therefore, for example, the inclination of the separator with respect to the second direction is gentle under the condition that the second distance is the same as compared with the configuration in which the first distance is equal to or less than the second distance, and as a result. , The stress generated in the single cell and the frame member in the first direction is small. Therefore, according to the present electrochemical reaction cell stack, it is possible to more effectively suppress the deterioration of the performance of the electrochemical reaction cell stack due to the displacement difference between the frame member and the single cell in the first direction.

(3) In the electrochemical reaction cell stack, in at least one cross section parallel to the first direction, the length of the connecting portion in the at least one separator is the length of the connecting portion in the at least one separator. From the shortest distance between the cell-side joint portion joined to the single cell and the frame-side joint portion joined to the frame member, the single cell and the frame member joined to the at least one separator. The length may be longer than the length obtained by subtracting the first distance, which is the distance in the third direction orthogonal to the first direction.

According to the electrochemical reaction cell stack, in at least one cross section parallel to the first direction, for example, the length of the connecting portion in at least one separator is the cell-side junction and the frame-side junction in the separator. The frame member is less than or equal to the length obtained by subtracting the first distance, which is the distance between the single cell and the frame member in the third direction orthogonal to the first direction, from the shortest distance to the portion. The stress generated in the single cell and the frame member due to the displacement difference between the single cell and the single cell in the first direction can be effectively relieved by the extension of the connecting portion of the separator.

(4) In the electrochemical reaction cell stack, in at least one cross section parallel to the first direction, among the at least one separator, a cell-side joint portion joined to the single cell and the frame. The second distance, which is the distance between the member and the frame-side joint portion joined in the first direction, may be larger than 0.01 mm. According to the present electrochemical reaction cell stack, it is particularly effective in a configuration in which the second distance, which is the distance between the cell-side joint portion and the frame-side joint portion in the separator in the first direction, is larger than 0.01 mm. ..

The technique disclosed in the present specification can be realized in various forms, for example, an electrochemical reaction cell stack (fuel cell stack or electrolytic cell stack), an electrochemical reaction cell stack including an electrochemical reaction cell stack. It can be realized in the form of a reaction system (fuel cell system or electrolytic cell system), their operation method, control method, and the like.

It is a perspective view which shows the appearance structure of the fuel cell stack 100 in this embodiment. It is explanatory drawing which shows the XZ cross-sectional structure of the fuel cell stack 100 at the position of II-II of FIG. It is explanatory drawing which shows the YZ cross-sectional structure of the fuel cell stack 100 at the position of III-III of FIG. It is explanatory drawing which shows the XZ cross section composition of two power generation units 102 adjacent to each other at the same position as the cross section shown in FIG. It is explanatory drawing which shows the YZ cross section configuration of two power generation units 102 adjacent to each other at the same position as the cross section shown in FIG. It is explanatory drawing which shows the XY cross-sectional structure of the power generation unit 102 at the position of VI-VI of FIG. It is explanatory drawing which enlarges and shows the XZ cross-sectional structure of the part (Px part of FIG. 4) of the 1st separator 120 and the 2nd separator 180 in this embodiment. It is explanatory drawing which enlarges and shows the XZ cross-sectional structure of the part of the 1st separator 120a in the modification.

A. Embodiment:
A-1. Device configuration:
(Structure of fuel cell stack 100)
FIG. 1 is a perspective view showing an external configuration of the fuel cell stack 100 in the present embodiment, and FIG. 2 is an XZ cross-sectional configuration of the fuel cell stack 100 at the position II-II in FIG. 1 (and FIG. 6 described later). 3 is an explanatory diagram showing a YZ cross-sectional configuration of the fuel cell stack 100 at the position III-III of FIG. 1 (and FIG. 6 described later). Each figure shows XYZ axes that are orthogonal to each other to identify the direction. In the present specification, for convenience, the Z-axis positive direction is referred to as an upward direction, and the Z-axis negative direction is referred to as a downward direction, but the fuel cell stack 100 is actually in a direction different from such an orientation. It may be installed. The same applies to FIGS. 4 and later. Further, in the present specification, the direction orthogonal to the Z axis is referred to as a plane direction. The plane direction corresponds to the second direction in the claims.

The fuel cell stack 100 includes a plurality of (seven in this embodiment) fuel cell power generation unit (hereinafter referred to as “power generation unit”) 102 and a pair of end plates 104 and 106. The seven power generation units 102 are arranged side by side in a predetermined arrangement direction (vertical direction in this embodiment). The pair of end plates 104 and 106 are arranged so as to sandwich an aggregate (hereinafter referred to as "cell block 103") composed of seven power generation units 102 from above and below. The arrangement direction (vertical direction) corresponds to the first direction in the claims, and the cell block 103 corresponds to the electrochemical reaction block in the claims.

A plurality of holes (eight in this embodiment) penetrating in the vertical direction are formed on the peripheral edge of each layer (power generation unit 102, end plates 104, 106) constituting the fuel cell stack 100 around the Z axis. , The holes formed in each layer and corresponding to each other communicate with each other in the vertical direction to form a communication hole 108 extending in the vertical direction from one end plate 104 to the other end plate 106. In the following description, the holes formed in each layer of the fuel cell stack 100 to form the communication holes 108 may also be referred to as communication holes 108.

A bolt 22 extending in the vertical direction is inserted into each communication hole 108, and the fuel cell stack 100 is fastened by the bolt 22 and the nuts 24 fitted on both sides of the bolt 22. As shown in FIGS. 2 and 3, between the nut 24 fitted on one side (upper side) of the bolt 22 and the upper surface of the end plate 104 constituting the upper end of the fuel cell stack 100, and the bolt. An insulating sheet 26 is interposed between the nut 24 fitted on the other side (lower side) of the 22 and the lower surface of the end plate 106 constituting the lower end of the fuel cell stack 100. However, in the place where the gas passage member 27 described later is provided, the insulating sheets arranged on the upper side and the lower side of the gas passage member 27 and the gas passage member 27 between the nut 24 and the surface of the end plate 106, respectively. 26 is intervening. The insulating sheet 26 is made of, for example, a mica sheet, a ceramic fiber sheet, a ceramic dust sheet, a glass sheet, a glass-ceramic composite agent, or the like.

The outer diameter of the shaft portion of each bolt 22 is smaller than the inner diameter of each communication hole 108. Therefore, a space is secured between the outer peripheral surface of the shaft portion of each bolt 22 and the inner peripheral surface of each communication hole 108. As shown in FIGS. 1 and 2, the position is near the midpoint of one side (the side on the positive side of the X axis among the two sides parallel to the Y axis) on the outer circumference of the fuel cell stack 100 around the Z axis. In the space formed by the bolt 22 (bolt 22A) and the communication hole 108 through which the bolt 22A is inserted, the oxidant gas OG is introduced from the outside of the fuel cell stack 100, and the oxidant gas OG is generated for each power generation. It functions as an oxidant gas introduction manifold 161 that is a gas flow path supplied to the unit 102, and is the midpoint of the side opposite to the side (the side on the negative side of the X-axis of the two sides parallel to the Y-axis). The space formed by the bolt 22 (bolt 22B) located in the vicinity and the communication hole 108 through which the bolt 22B is inserted contains the oxidizing agent off-gas OOG which is the gas discharged from the air chamber 166 of each power generation unit 102. It functions as an oxidant gas discharge manifold 162 that discharges to the outside of the fuel cell stack 100. In this embodiment, air is used as the oxidant gas OG. Further, in the present embodiment, a blower (not shown) is used for introducing the oxidant gas OG into the oxidant gas introduction manifold 161. Further, it is generated when heat exchange (for example, the oxidant off-gas OOG and the fuel off-gas FOG discharged from the fuel cell stack 100 are burned) before the oxidant gas OG is introduced into the oxidant gas introduction manifold 161. Preheating of the oxidizing agent gas OG may be performed by utilizing heat exchange with heat).

Further, as shown in FIGS. 1 and 3, the vicinity of the midpoint of one side (the side on the positive side of the Y axis among the two sides parallel to the X axis) on the outer circumference of the fuel cell stack 100 around the Z axis. In the space formed by the bolt 22 (bolt 22D) located at the center and the communication hole 108 through which the bolt 22D is inserted, the fuel gas FG is introduced from the outside of the fuel cell stack 100, and the fuel gas FG is generated for each power generation. A bolt 22 that functions as a fuel gas introduction manifold 171 to be supplied to the unit 102 and is located near the midpoint of the opposite side (the side on the negative side of the Y axis among the two sides parallel to the X axis). The space formed by (bolt 22E) and the communication hole 108 through which the bolt 22E is inserted causes the fuel off-gas FOG, which is the gas discharged from the fuel chamber 176 of each power generation unit 102, to the outside of the fuel cell stack 100. It functions as a fuel gas discharge manifold 172 to be discharged. In this embodiment, as the fuel gas FG, for example, a hydrogen-rich gas obtained by reforming a city gas is used.

The fuel cell stack 100 is provided with four gas passage members 27. Each gas passage member 27 has a hollow cylindrical main body portion 28 and a hollow cylindrical branch portion 29 branched from the side surface of the main body portion 28. The hole of the branch portion 29 communicates with the hole of the main body portion 28. A gas pipe (not shown) is connected to the branch portion 29 of each gas passage member 27. Further, as shown in FIG. 2, the hole of the main body 28 of the gas passage member 27 arranged at the position of the bolt 22A forming the oxidant gas introduction manifold 161 communicates with the oxidant gas introduction manifold 161. The hole of the main body 28 of the gas passage member 27 arranged at the position of the bolt 22B forming the oxidant gas discharge manifold 162 communicates with the oxidant gas discharge manifold 162. Further, as shown in FIG. 3, the hole of the main body 28 of the gas passage member 27 arranged at the position of the bolt 22D forming the fuel gas introduction manifold 171 communicates with the fuel gas introduction manifold 171 and fuel gas. The hole of the main body 28 of the gas passage member 27 arranged at the position of the bolt 22E forming the discharge manifold 172 communicates with the fuel gas discharge manifold 172.

(Structure of end plates 104 and 106)
The pair of end plates 104 and 106 are substantially rectangular flat plate-shaped conductive members, and are made of, for example, stainless steel. One end plate 104 is located above the power generation unit 102 located at the top, and the other end plate 106 is located below the power generation unit 102 located at the bottom. A plurality of power generation units 102 are sandwiched by a pair of end plates 104 and 106 in a pressed state. The upper end plate 104 functions as a positive output terminal of the fuel cell stack 100, and the lower end plate 106 functions as a negative output terminal of the fuel cell stack 100. The pair of end plates 104 and 106 correspond to a pair of end members within the scope of the claims.

(Structure of power generation unit 102)
FIG. 4 is an explanatory diagram showing an XZ cross-sectional configuration of two power generation units 102 adjacent to each other at the same position as the cross section shown in FIG. 2, and FIG. 5 is an explanatory view showing the XZ cross-sectional configuration of the two power generation units 102 adjacent to each other at the same position as the cross section shown in FIG. It is explanatory drawing which shows the YZ cross-sectional structure of two power generation units 102. Further, FIG. 6 is an explanatory diagram showing an XY cross-sectional configuration of the power generation unit 102 at the position of VI-VI in FIG.

As shown in FIGS. 4 and 5, the power generation unit 102 includes a single cell 110, a first separator 120, an air pole side frame 130, an air pole side current collector 134, and a fuel pole side frame 140. It includes a current collector 144 on the fuel electrode side, a pair of interconnectors 150 constituting the uppermost layer and the lowermost layer of the power generation unit 102, and a second separator 180. A hole corresponding to the communication hole 108 into which the bolt 22 described above is inserted is formed in the peripheral portion around the Z axis in the first separator 120, the air pole side frame 130, the fuel pole side frame 140, and the second separator 180. Has been done. As described above, since the fuel cell stack 100 includes a plurality of (seven in the present embodiment) power generation units 102, the fuel cell stack 100 has a plurality of (seven in the present embodiment) single cells. It can be said that it has 110.

The interconnector 150 is a substantially rectangular flat plate-shaped conductive member, and is made of, for example, ferritic stainless steel. The interconnector 150 ensures electrical conduction between the power generation units 102 and prevents mixing of the reaction gas between the power generation units 102. In this embodiment, when two power generation units 102 are arranged adjacent to each other, one interconnector 150 is shared by two adjacent power generation units 102. That is, the upper interconnector 150 in one power generation unit 102 is the same member as the lower interconnector 150 in another power generation unit 102 adjacent to the upper side of the power generation unit 102. Further, since the fuel cell stack 100 includes a pair of end plates 104 and 106, the power generation unit 102 located at the top of the fuel cell stack 100 does not have the upper interconnector 150 and is located at the bottom. The power generation unit 102 does not include the lower interconnector 150 (see FIGS. 2 and 3).

The single cell 110 includes an electrolyte layer 112, an air electrode (cathode) 114 and a fuel electrode (anode) 116 facing each other in the vertical direction (arrangement direction in which the power generation units 102 are arranged) with the electrolyte layer 112 interposed therebetween. The single cell 110 of the present embodiment is a flat plate type single cell, and is a fuel pole support type single cell in which the electrolyte layer 112 and the air pole 114 are supported by the fuel pole 116.

The electrolyte layer 112 is a flat plate-shaped member having a substantially rectangular shape in the Z-axis direction, and is a dense layer. The electrolyte layer 112 is formed of, for example, a solid oxide such as YSZ (yttria-stabilized zirconia), ScSZ (scandia-stabilized zirconia), SDC (samarium-doped ceria), GDC (gadolinium-doped ceria), and perovskite-type oxide. There is. As described above, the single cell 110 of the present embodiment is a solid oxide fuel cell (SOFC) using a solid oxide as an electrolyte. The air electrode 114 is a substantially rectangular flat plate-shaped member smaller than the electrolyte layer 112 in the Z-axis direction, and is a porous layer. The air electrode 114 is formed of, for example, a perovskite-type oxide (for example, LSCF (lanternstrontium cobalt iron oxide), LSM (lanternstrontium manganese oxide), LNF (lantern nickel iron)). The fuel electrode 116 is a substantially rectangular flat plate-shaped member having substantially the same size as the electrolyte layer 112 in the Z-axis direction, and is a porous layer. The fuel electrode 116 is formed of, for example, a cermet composed of Ni and oxide ion conductive ceramic particles (for example, YSZ).

The first separator 120 is a frame-shaped member in which a substantially rectangular first separator through hole 121 penetrating in the vertical direction is formed near the center, and is formed of, for example, metal. As shown in FIG. 6, the portion of the first separator 120 that surrounds the first separator through hole 121 (hereinafter referred to as “first through hole peripheral portion 122”) is one side of the single cell 110 in the vertical direction (hereinafter referred to as “first through hole peripheral portion 122”). It faces the peripheral edge of the surface (upper side in the drawing). In the present embodiment, since the size of the air electrode 114 in the Z-axis direction is smaller than that of the electrolyte layer 112, the first through-hole peripheral portion 122 of the first separator 120 is the upper surface of the single cell 110. Inside, it faces the surface composed of the electrolyte layer 112. The first separator 120 is bonded to the single cell 110 (electrolyte layer 112) by a bonding portion 124 formed of a brazing material (for example, Ag wax) arranged at the facing portions thereof. The first separator 120 partitions the air chamber 166 facing the air pole 114 and the fuel chamber 176 facing the fuel pole 116.

The air pole side frame 130 is a frame-shaped member in which a substantially rectangular air chamber hole 131 penetrating in the vertical direction is formed near the center, and is formed of, for example, an insulator such as mica. The air chamber hole 131 of the air pole side frame 130 constitutes an air chamber 166 facing the air pole 114. The air electrode side frame 130 includes a peripheral edge of the surface of the first separator 120 opposite to the side facing the electrolyte layer 112 and a peripheral edge of the surface of the second separator 180 facing the air electrode 114. Is in contact with. That is, the air electrode side frame 130 is sandwiched between the first separator 120 and the second separator 180. Therefore, the air chamber 166 seal (compression seal) is realized by the air electrode side frame 130. Further, the air electrode side frame 130 electrically insulates between the pair of interconnectors 150 and the second separator 180 included in the power generation unit 102. Further, in the air electrode side frame 130, the oxidant gas supply communication flow path 132 that communicates the oxidant gas introduction manifold 161 and the air chamber 166, and the oxidant that communicates the air chamber 166 and the oxidant gas discharge manifold 162. A gas discharge communication flow path 133 is formed.

The fuel pole side frame 140 is a frame-shaped member in which a substantially rectangular fuel chamber hole 141 penetrating in the vertical direction is formed near the center, and is formed of, for example, metal. The fuel electrode side frame 140 is in contact with the peripheral edge of the surface of the first separator 120 facing the electrolyte layer 112 and the peripheral edge of the surface of the second separator 180 facing the fuel electrode 116. (See FIGS. 4 and 5). The air pole side frame 130 and the fuel pole side frame 140 correspond to the frame member in the claims, and the air chamber hole 131 and the fuel chamber hole 141 correspond to the frame through holes in the claims. ..

As shown in FIG. 6, the air pole side current collector 134 is arranged in the air chamber 166. The air electrode side current collector 134 is composed of a plurality of substantially square columnar current collector elements 135, and is formed of, for example, ferritic stainless steel. The air pole side current collector 134 is in contact with the surface of the air pole 114 on the side opposite to the side facing the electrolyte layer 112 and the surface of the interconnector 150 on the side facing the air pole 114. However, as described above, since the power generation unit 102 located at the top of the fuel cell stack 100 does not have the upper interconnector 150, the air electrode side current collector 134 in the power generation unit 102 is the top-level first. It is in contact with the separator 180 of 2, and is electrically connected to the upper end plate 104 via the second separator 180. Since the current collector 134 on the air electrode side has such a configuration, the air electrode 114 and the interconnector 150 (or the end plate 104) are electrically connected to each other. The air electrode side current collector 134 may be covered with a conductive coat, and a conductive bonding layer for bonding the air electrode 114 and the air electrode side current collector 134 may be provided between the air electrode 114 and the air electrode side current collector 134. It may be intervening. Further, the air electrode side current collector 134 may be configured as a member integrated with the interconnector 150.

The fuel electrode side current collector 144 is arranged in the fuel chamber 176. The fuel electrode side current collector 144 includes an interconnector facing portion 146, an electrode facing portion 145, and a connecting portion 147 connecting the electrode facing portion 145 and the interconnector facing portion 146, for example, nickel or nickel alloy. , Stainless steel, etc. The electrode facing portion 145 is in contact with the surface of the fuel electrode 116 opposite to the side facing the electrolyte layer 112, and the interconnector facing portion 146 is on the surface of the interconnector 150 on the side facing the fuel pole 116. Are in contact. However, as described above, since the power generation unit 102 located at the bottom of the fuel cell stack 100 does not have the lower interconnector 150, the interconnector facing portion 146 in the power generation unit 102 is an intermediate member 190 described later. Is in contact with, and is electrically connected to the lower end plate 106 via the intermediate member 190. Since the current collector 144 on the fuel electrode side has such a configuration, the fuel electrode 116 and the interconnector 150 (or the end plate 106) are electrically connected to each other. A spacer 149 formed of, for example, a mica is arranged between the electrode facing portion 145 and the interconnector facing portion 146. Therefore, the fuel electrode side current collector 144 follows the deformation of the power generation unit 102 due to the temperature cycle and the reaction gas pressure fluctuation, and the fuel electrode 116 and the interconnector 150 (or the end plate 106) via the fuel electrode side current collector 144 follow. Good electrical connection with is maintained.

A-2. Operation of fuel cell stack 100:
As shown in FIGS. 2, 4 and 6, the oxidant gas is passed through a gas pipe (not shown) connected to the branch portion 29 of the gas passage member 27 provided at the position of the oxidant gas introduction manifold 161. When the OG is supplied, the oxidant gas OG is supplied to the oxidant gas introduction manifold 161 through the holes of the branch portion 29 and the main body portion 28 of the gas passage member 27, and each power generation unit is supplied from the oxidant gas introduction manifold 161. It is supplied to the air chamber 166 via the oxidizing agent gas supply communication flow path 132 of 102. Further, as shown in FIGS. 3 and 5, the fuel gas FG is supplied via a gas pipe (not shown) connected to the branch portion 29 of the gas passage member 27 provided at the position of the fuel gas introduction manifold 171. Then, the fuel gas FG is supplied to the fuel gas introduction manifold 171 through the holes of the branch portion 29 and the main body portion 28 of the gas passage member 27, and the fuel gas supply communication of each power generation unit 102 is performed from the fuel gas introduction manifold 171. It is supplied to the fuel chamber 176 via the flow path 142.

When the oxidizing agent gas OG is supplied to the air chamber 166 of each power generation unit 102 and the fuel gas FG is supplied to the fuel chamber 176, oxygen contained in the oxidizing agent gas OG and hydrogen contained in the fuel gas FG in the single cell 110 are supplied. Power is generated by an electrochemical reaction with. This power generation reaction is an exothermic reaction. In each power generation unit 102, the air pole 114 of the single cell 110 is electrically connected to one of the interconnectors 150 via the air pole side current collector 134, and the fuel pole 116 is via the fuel pole side current collector 144. It is electrically connected to the other interconnector 150. Further, the plurality of power generation units 102 included in the fuel cell stack 100 are electrically connected in series. Therefore, the electric energy generated in each power generation unit 102 is taken out from the end plates 104 and 106 that function as the output terminals of the fuel cell stack 100. Since the SOFC generates electricity at a relatively high temperature (for example, 700 ° C. to 1000 ° C.), the fuel cell stack 100 is a heater (for example, until the high temperature can be maintained by the heat generated by the power generation after the start-up. It may be heated by (not shown).

The oxidant off-gas OOG discharged from the air chamber 166 of each power generation unit 102 is discharged to the oxidant gas discharge manifold 162 via the oxidant gas discharge communication flow path 133 as shown in FIGS. 2, 4 and 6. Further, through the holes of the main body portion 28 and the branch portion 29 of the gas passage member 27 provided at the position of the oxidizing agent gas discharge manifold 162, and via a gas pipe (not shown) connected to the branch portion 29. It is discharged to the outside of the fuel cell stack 100. Further, as shown in FIGS. 3 and 5, the fuel off-gas FOG discharged from the fuel chamber 176 of each power generation unit 102 is discharged to the fuel gas discharge manifold 172 via the fuel gas discharge communication flow path 143, and further fuels. The outside of the fuel cell stack 100 via a gas pipe (not shown) connected to the branch portion 29 through the holes of the main body portion 28 and the branch portion 29 of the gas passage member 27 provided at the position of the gas discharge manifold 172. Is discharged to.

A-3. Relationship between single cell 110 and frames 130, 140 and pair of end plates 104, 106 in cell block 103:
As shown in FIGS. 1 to 3, in the fuel cell stack 100 of the present embodiment, the end plates 104 and 106 are formed with opening windows 104A and 106A penetrating in the vertical direction (arrangement direction of the single cells 110). ing. That is, in each of the end plates 104 and 106, spaces S1 and S2 that open on both the upper and lower sides (the cell block 103 side and the side opposite to the cell block 103) are formed by the opening windows 104A and 106A. In the vertical view, the contour lines of the spaces S1 and S2 include the single cell 110. In other words, the contour lines of the spaces S1 and S2 are located outside the outline of the single cell 110 over the entire circumference. In the vertical view, the end plates 104 and 106 do not overlap the cell block 103 but overlap the frames 130 and 140.

An intermediate member 190 is arranged between the cell block 103 and the lower end plate 106. The intermediate member 190 is a flat plate-shaped member having no through hole formed therein, and is formed of, for example, metal. A fuel pole side current collector 144 located at the lowermost position of the cell block 103 is joined to the vicinity of the center of the intermediate member 190, and the peripheral portion of the intermediate member 190 is joined to the cell block 103 and the lower end plate 106. It is sandwiched between. That is, the cell block 103 is supported by the first separator 120, the second separator 180, and the intermediate member 190 for each of the frames 130 and 140. The thickness of the first separator 120, the second separator 180, and the intermediate member 190 in the vertical direction is thinner than the vertical thickness of each of the frames 130 and 140, and is smaller than that of the frames 130 and 140. Highly flexible.

With the above configuration, the fuel cell stack 100 includes a plurality of fastening members (bolts 22, nuts 24), and the plurality of fastening members span the pair of end plates 104, 106 and the frames 130, 140 in the cell block 103. It is inserted into each of the plurality of communication holes 108 formed, and the fuel cell stack 100 is fastened by the plurality of fastening members. Specifically, the portion of the fuel cell stack 100 (cell block 103) that overlaps the end plates 104 and 106 in the vertical direction (mainly the frames 130 and 140) is sandwiched between the pair of end plates 104 and 106. , Receives a relatively large load due to the fastening force of the fastening member (bolt 22, nut 24) that fastens the pair of end plates 104, 106. As a result, the frames 130 and 140 realize the sealing of the air chamber 166 and the fuel chamber 176. On the other hand, in the fuel cell stack 100, the portion (mainly the single cell 110) that does not overlap with the end plates 104 and 106 in the vertical direction directly applies the load due to the fastening force of the fastening member that fastens the pair of end plates 104 and 106. I don't receive it. That is, the single cell 110 and the frames 130, 140 in the fuel cell stack 100 differ from each other in the magnitude of the load received in the vertical direction from the pair of end plates 104, 106. As a result, a relatively large load required to realize the sealing of the air chamber 166 and the fuel chamber 176 is applied to the frames 130 and 140, and the single cell 110 is provided with the conductivity between the single cells 110. It is possible to prevent an unnecessarily large load from being applied while ensuring the above.

A-4. Detailed configuration of the first separator 120:
FIG. 7 is an explanatory view showing an enlarged XZ cross-sectional configuration of a part (Px portion of FIG. 4) of the first separator 120 and the second separator 180. The vertical thickness (for example, 0.1 mm) of the first separator 120 is thinner than the vertical thickness (for example, 1 mm) of each of the frames 130 and 140. The first separator 120 corresponds to a separator in the claims.

The first separator 120 includes a first inner portion 126 including a first through hole peripheral portion 122, and a first outer portion 127 located on the outer peripheral side of the first inner portion 126. The positions of the first inner portion 126 and the first outer portion 127 in the Z-axis direction are substantially the same as each other. The position of the first inner portion 126 in the Z-axis direction is the first inner portion 126 on the surface of the surface of the first inner portion 126 facing the air chamber 166 (upper side). It means the position of the highest part in. The position of the first outer portion 127 in the Z-axis direction is the most on the surface of the first outer portion 127 on the side (upper side) facing the air chamber 166 in the surface of the first outer portion 127. It means the position of the part located above. Further, the first inner portion 126 corresponds to the inner portion in the claims, and the first outer portion 127 corresponds to the outer portion in the claims.

The first separator 120 further comprises a first connecting portion 128 connecting the end of the first inner portion 126 and the end of the first outer portion 127. In the present embodiment, the first connecting portion 128 has a shape curved so as to project from the positions of the first inner portion 126 and the first outer portion 127 toward the fuel chamber 176 side (lower side). .. That is, the fuel chamber 176 side (lower side) of the first connecting portion 128 is a convex portion, and the air chamber 166 side (upper side) of the first connecting portion 128 is a concave portion. As described above, the first connecting portion 128 includes a portion whose position in the Z-axis direction is different from that of the first inner portion 126 and the first outer portion 127. The first connecting portion 128 is formed so as to surround the first separator through hole 121 in the Z-axis direction. Further, the first connecting portion 128 in the first separator 120 is formed by, for example, press working. Since the first connecting portion 128 of the first separator 120 has the above-described configuration, it functions like a spring that easily expands and contracts in the plane direction. Therefore, the first separator 120 of the present embodiment is more likely to be deformed in the plane direction at the position of the first connecting portion 128 as compared with the configuration not provided with the first connecting portion 128. Further, the thickness t ₁ (plate thickness) of the first separator 120 in the vertical direction may be 0.01 (mm) or more, and is preferably 0.03 (from the viewpoint of suppressing deterioration of oxidation resistance). mm) or more, more preferably 0.05 (mm) or more, and preferably 0.2 (mm) or less. By setting the thickness t ₁ of the first separator 120 to 0.03 (mm) or more, it is possible to suppress a decrease in the oxidation resistance of the first separator 120, and the thickness t of the first separator 120 By setting ₁ to 0.2 (mm) or less, the springiness of the first connecting portion 128 can be ensured to a certain extent or more.

As shown in FIG. 7, the depth H ₁ of the first connecting portion is more preferably 0.1 (mm) or more and 2.0 (mm) or less. By setting the depth H ₁ of the first connecting portion to 0.1 (mm) or more, the effect of suppressing deformation or cracking of the single cell 110 by the first connecting portion 128 can be ensured. Further, if the depth H ₁ of the first connecting portion is higher than 2.0 (mm), the gas flow may be obstructed by the first connecting portion 128 and the power generation performance may be deteriorated, which is not preferable. By setting the depth H _{1 of the connecting portion 1} to 2.0 (mm) or less, it is possible to prevent the first connecting portion 128 from obstructing the gas flow and deteriorating the power generation performance.

Further, it is preferable that the depth H ₁ of the first connecting portion is larger than the thickness t ₁ of the first separator 120. By making the depth H ₁ of the first connecting portion larger than the thickness t ₁ of the first separator 120, it is possible to secure the effect of suppressing the deformation and cracking of the single cell 110 by the first connecting portion 128. .. The first connecting portion 128 corresponds to the connecting portion within the scope of the claims.

Further, in FIG. 6, in a vertical view, a region within the contour lines of the opening windows 104A and 106A formed on the end plates 104 and 106 is formed by two diagonal lines (virtual straight lines) of the contour lines (rectangles). The first to fourth compartment areas E1 to E4 formed by dividing into four equal parts are shown. In the present embodiment, the first separator 120 is formed so that the first connecting portion 128 is located in all the regions of the first to fourth compartment regions E1 to E4. Specifically, in the first separator 120, the first connecting portion 128 is continuously formed along the peripheral edge portion of the first separator 120 over the entire circumference. The shapes of the opening windows 104A and 106A formed on the end plates 104 and 106 are not limited to a rectangle, and may be, for example, a circle.

Further, the first separator 120 passes through the center O of the single cell 110 in the vertical direction (Z-axis direction) and further satisfies the following first requirement in all the cross sections parallel to the vertical direction. (See Fig. 7). In the same cross section, the direction (X-axis direction) orthogonal to the vertical direction (Z-axis direction) corresponds to the third direction in the claims.
<First requirement>
"First distance ΔX1">"Second distance ΔZ1"
First distance ΔX1: Distance between the single cell 110 and the air electrode side frame 130 (a frame located on the same side as the single cell 110 with respect to the first separator 120 in the vertical direction) in the vertical direction. ΔZ1: The vertical distance between the cell-side joint portion 123 joined to the single cell 110 and the frame-side joint portion 129 joined to the air electrode side frame 130 in the first separator 120.

Further, the first separator 120 passes through the center O of the single cell 110 in the vertical direction (Z-axis direction) and further satisfies the following second requirement in all the cross sections parallel to the vertical direction. (See Fig. 7).
<Second requirement>
"Length ΔC1 of the first connecting portion 128">"Minimum distance ΔB1 between the cell side joining portion 123 and the frame side joining portion 129"-"First distance ΔX1"
Length of the first connecting portion 128 ΔC1: The shortest distance between the first inner portion 126 and the first outer portion 127 on the inner peripheral surface of the first connecting portion 128 Cell-side joint portion 123 and the frame. It is a value obtained by dividing the first distance ΔX1 from the square root of the shortest distance ΔB1: [(first distance ΔX1) ² + (second distance ΔZ1) ² ] with the side joint portion 129.

Further, the first separator 120 passes through the center O of the single cell 110 in the vertical direction (Z-axis direction) and further satisfies the following third requirement in all the cross sections parallel to the vertical direction. (See Fig. 7).
<Third requirement>
"Second distance ΔZ1"> 0.01 mm

A-5. Detailed configuration of the second separator 180:
The second separator 180 includes a second inner portion 186 including a second through hole peripheral portion 182, and a second outer portion 187 located on the outer peripheral side of the second inner portion 186. The positions of the second inner portion 186 and the second outer portion 187 in the Z-axis direction are substantially the same as each other. The position of the second inner portion 186 in the Z-axis direction is the second inner portion 186 on the surface of the surface of the second inner portion 186 on the side facing the fuel chamber 176 (upper side). It means the position of the highest part in. The position of the second outer portion 187 in the Z-axis direction is the most on the surface of the second outer portion 187 on the side (upper side) facing the fuel chamber 176 in the surface of the second outer portion 187. It means the position of the part located above.

The second separator 180 further comprises a second connecting portion 188 that connects the end of the second inner portion 186 and the end of the second outer portion 187. In the present embodiment, the second connecting portion 188 has a curved shape so as to project from the positions of the second inner portion 186 and the second outer portion 187 toward the fuel chamber 176 side (lower side). .. That is, the fuel chamber 176 side (lower side) of the second connecting portion 188 is a convex portion, and the air chamber 166 side (upper side) of the second connecting portion 188 is a concave portion. As described above, the second connecting portion 188 includes a portion whose position in the Z-axis direction is different from that of the second inner portion 186 and the second outer portion 187. The second connecting portion 188 is formed so as to surround the second separator through hole 181 in the Z-axis direction. Further, the second connecting portion 188 in the second separator 180 is formed by, for example, press working. Since the second connecting portion 188 of the second separator 180 has the above-described configuration, it functions like a spring that easily expands and contracts in the plane direction. Therefore, the second separator 180 of the present embodiment is more likely to be deformed in the plane direction at the position of the second connecting portion 188 as compared with the configuration not provided with the second connecting portion 188. Further, the thickness t ₂ (plate thickness) of the second separator 180 in the vertical direction may be 0.01 (mm) or more, and is preferably 0.03 (from the viewpoint of suppressing deterioration of oxidation resistance). mm) or more, more preferably 0.05 (mm) or more, and preferably 0.2 (mm) or less. By setting the thickness t ₂ of the second separator 180 to 0.03 (mm) or more, it is possible to suppress a decrease in the oxidation resistance of the second separator 180, and the thickness t of the second separator 180. By setting ₂ to 0.2 (mm) or less, the springiness of the second connecting portion 188 can be ensured to a certain extent or more.

As shown in FIG. 7, the depth H ₂ of the second connecting portion is more preferably 0.1 (mm) or more and 2.0 (mm) or less. By setting the depth H ₂ of the second connecting portion to 0.1 (mm) or more, the effect of suppressing deformation or cracking of the single cell 110 by the second connecting portion 188 can be ensured. Further, if the depth H ₂ of the second connecting portion is higher than 2.0 (mm), the gas flow may be obstructed by the second connecting portion 188 and the power generation performance may be deteriorated, which is not preferable. By setting the depth H _{2 of the connecting portion 2} to 2.0 (mm) or less, it is possible to prevent the second connecting portion 188 from obstructing the gas flow and deteriorating the power generation performance.

Further, it is preferable that the depth H ₂ of the second connecting portion is larger than the thickness t ₂ of the second separator 180. By making the depth H ₂ of the second connecting portion larger than the thickness t ₂ of the second separator 180, it is possible to secure the effect of suppressing the deformation and cracking of the single cell 110 by the second connecting portion 188. ..

Further, in the present embodiment, similarly to the first separator 120 described above, in the second separator 180, the second connecting portion 188 is located in all the regions of the first to fourth compartment regions E1 to E4. It is formed like this. Specifically, in the second separator 180, a second connecting portion 188 is continuously formed along the peripheral edge portion of the second separator 180 over the entire circumference.

Further, the second separator 180 passes through the center O of the single cell 110 in the vertical direction (Z-axis direction) and further satisfies the following fourth requirement in all cross sections parallel to the vertical direction. (See Fig. 7).
<Fourth requirement>
"First distance ΔX2">"Second distance ΔZ2"
First distance ΔX2: Distance between the single cell 110 and the air electrode side frame 130 (a frame located on the same side as the single cell 110 with respect to the second separator 180 in the vertical direction) in the vertical direction. ΔZ2: Vertical distance between the connector side joint portion 183 joined to the interconnector 150 and the frame side joint portion 189 joined to the fuel electrode side frame 140 in the second separator 180.

Further, the second separator 180 passes through the center O of the single cell 110 in the vertical direction (Z-axis direction) and further satisfies the following fifth requirement in all the cross sections parallel to the vertical direction. (See Fig. 7).
<Fifth requirement>
"Length ΔC2 of the second connecting portion 188">"Shortest distance ΔB2 between the connector side joint portion 183 and the frame side joint portion 189"-"First distance ΔX2"
Length of second connecting portion 188 ΔC2: Shortest distance between the second inner portion 186 and the second outer portion 187 on the inner peripheral surface of the second connecting portion 188 Connector-side joint portion 183 and the frame. The shortest distance ΔB2 from the side junction 189: [(first distance ΔX2) ² + (second distance ΔZ2) ² ] is the value obtained by dividing the first distance ΔX2 from the square root.

Further, the second separator 180 passes through the center O of the single cell 110 in the vertical direction (Z-axis direction) and further satisfies the following sixth requirement in all the cross sections parallel to the vertical direction. (See Fig. 7).
<Sixth requirement>
"Second distance ΔZ2"> 0.01 mm

A-6. Effect of this embodiment:
As described above, in the fuel cell stack 100 of the present embodiment, the space S1 is formed in the end plates 104 and 106. The space S1 is open at least on the cell block 103 side, and the contour line includes the single cell 110 in the vertical view, which is the direction in which the plurality of power generation units 102 (single cell 110) are arranged. In the fuel cell stack 100 in which the space S1 is formed in the end plates 104 and 106 in this way, for example, the space is not formed in the end plates 104 and 106, and the entire surface of the end plates 104 and 106 on the cell block 103 side is the entire surface. Compared to the configuration in which the cells are flat, the frames 130, 140 and the single cell 110 in the cell block 103 are simply different from the end plates 104, 106 due to the different loads received from the pair of end plates 104, 106. Displacement difference in the vertical direction from the cell 110 (displacement difference in the vertical direction between the cell-side joint portion 123 and the frame-side joint portion 129 shown in FIG. 7) is likely to occur. Then, for example, due to a thermal cycle, heat shock, or the like, the displacement difference between the end plates 104, 106 and the single cell 110 in the vertical direction becomes even larger. When a displacement difference occurs in the vertical direction between the end plates 104 and 106 and the single cell 110, for example, the single cell 110 is pulled in the vertical direction via the first separator 120, so that the single cell 110 is cracked. In addition, the sealing performance of the end plates 104 and 106 may be deteriorated, and the performance of the fuel cell stack 100 may be deteriorated.

On the other hand, according to the fuel cell stack 100 of the present embodiment, the first connecting portion 128 of the first separator 120 functions like a spring that easily expands and contracts, and the first separator 120 is the first. Since it is easily deformed at the position of the connecting portion 128 (see FIG. 7), when the displacement difference between the end plates 104 and 106 and the single cell 110 in the vertical direction becomes large, the first separator 120 mainly becomes the first connecting portion 128. As a result, the stress generated in the single cell 110 and the end plates 104 and 106 is relaxed due to the displacement difference, so that the displacement of the end plates 104 and 106 and the single cell 110 in the vertical direction is relaxed. It is possible to suppress the deterioration of the performance of the fuel cell stack 100 due to the difference.

Further, in the present embodiment, the first separator 120 is formed so that the first connecting portion 128 is located in all the regions of the first to fourth compartment regions E1 to E4 (see FIG. 6). ). Therefore, according to the present embodiment, the function of stress relaxation is exerted over the entire circumference of the first separator 120, and therefore, for example, the first connection to any of the first to fourth partition regions E1 to E4. Compared with the configuration in which the portion 128 is not formed, the deterioration of the performance of the fuel cell stack 100 due to the displacement difference between the end plates 104 and 106 and the single cell 110 in the vertical direction can be more effectively suppressed. ..

Further, in the present embodiment, the first distance ΔX1, which is the distance between the single cell 110 joined to the first separator 120 and the frames 130, 140 in the vertical direction, is the cell side joining in the first separator 120. It is longer than the second distance ΔZ1, which is the vertical distance between the portion 123 and the frame-side joint portion 129 (see the first requirement FIG. 7 above). Here, FIG. 8 is an explanatory view showing an enlarged XZ cross-sectional structure of a part of the first separator 120a in the modified example. In the modified fuel cell stack 100a, the first distance ΔX1 is equal to or less than the second distance ΔZa (> ΔZ1). Therefore, the second inclination (angle θ1a> above angle θ1) of the first separator 120a with respect to the surface direction becomes relatively steep, and as a result, the stress in the vertical direction generated in the single cell 110 and the frames 130 and 140 becomes relatively steep. Is relatively large. On the other hand, according to the present embodiment, the inclination of the first separator 120 with respect to the plane direction (see angle θ1) under the condition that the second distance ΔZa is the same as that of the fuel cell stack 100a of the modified example. ) Is relatively gentle, and as a result, the stress generated in the single cell and the frame member in the first direction is small. Therefore, according to the present embodiment, it is possible to more effectively suppress the deterioration of the performance of the fuel cell stack 100 due to the vertical displacement difference between the end plates 104 and 106 and the single cell 110.

In the present embodiment, the length ΔC1 of the first connecting portion 128 in the first separator 120 is the first from the shortest distance ΔB1 between the cell-side joint portion 123 and the frame-side joint portion 129 in the first separator 120. It is longer than the length obtained by subtracting the distance ΔX1 (see FIG. 7). Therefore, according to the present embodiment, the frames 130 and 140 and the single cell have a length ΔC1 of the first connecting portion 128 shorter than the length obtained by subtracting the first distance ΔX1 from the shortest distance ΔB1. The stress generated in the single cell 110 and the frames 130 and 140 due to the displacement difference in the vertical direction from the 110 can be effectively relieved by the extension of the first connecting portion 128 of the first separator 120.

Further, according to the present embodiment, in a configuration in which the second distance ΔZ1, which is the vertical distance between the cell-side joint portion 123 and the frame-side joint portion 129 in the first separator 120, is larger than 0.01 mm. Especially effective.

B. Modification example:
The technique disclosed in the present specification is not limited to the above-described embodiment, and can be transformed into various forms without departing from the gist thereof, and for example, the following modifications are also possible.

The configuration of the single cell 110, the power generation unit 102, or the fuel cell stack 100 in the above embodiment is merely an example and can be variously modified. For example, in the above embodiment, a space may be formed only on one of the pair of end plates 104 and 106. Further, in the above embodiment, the spaces S1 and S2 penetrating the end plates 104 and 106 are exemplified as the space, but the space is opened, for example, on the cell block 103 side and on the opposite side of the cell block 103. It may be a concave space that does not have a recess. Further, in the above embodiment, the flat plate-shaped end plates 104 and 106 are exemplified as the end member, but the end member may have a shape other than the flat plate shape. Further, in the above embodiment, the shape of the end member in the vertical direction is a frame shape, but for example, in the above embodiment, the shapes of the end plates 104 and 106 are formed on the outer periphery of the fuel cell stack 100 around the Z axis. A portion along each of the three sides (for example, a portion fastened with seven bolts 22 excluding any one of the bolts 22A, 22B, 22D, 22E) and a portion along the remaining one side. The shape may not be provided, or six bolts excluding one set of bolts 22A and 22B or bolts 22D and 22E along two parallel sides of the outer circumference of the fuel cell stack 100 around the Z axis. It may have a shape having a portion to be fastened at 22) and not having a portion along the remaining two sides.

Further, in the above embodiment, the intermediate member 190 may have a structure in which a through hole is formed.

Further, in the above embodiment, all the first separators 120 provided in the fuel cell stack 100 are provided with the first connecting portion 128, but all the first separators 120 provided in the fuel cell stack 100 are provided. If at least one of the above is provided with the first connecting portion 128, it is possible to suppress the deterioration of the performance of the fuel cell stack 100 due to the difference in the vertical displacement between the frames 130, 140 and the single cell 110. Of all the first separators 120 provided in the fuel cell stack 100, it is preferable that 50% or more of the first separators 120 have the first connecting portion 128, and all the first separators 120 have a configuration. Of these, a configuration in which 80% or more of the first separator 120 includes the first connecting portion 128 is more preferable. Further, in particular, in the power generation unit 102 arranged at a position away from the end plates 104 and 106 in the vertical direction, a displacement difference in the vertical direction between the frames 130 and 140 and the single cell 110 is likely to occur. Therefore, the first separator 120 (the first separator 120 located on the central side in the vertical direction in the fuel cell stack 100) arranged at a position away from the end plates 104 and 106 in the vertical direction is the first connecting portion. A configuration including 128 is preferred.

Further, in the above embodiment, it is assumed that all the cross sections passing through the center O of the single cell 110 in the vertical direction (Z-axis direction) and parallel to the vertical direction satisfy the first to sixth requirements. However, the present invention is not limited to this, and the first to sixth requirements may be satisfied in at least one cross section that passes through the center O of the single cell 110 in the vertical direction) and is parallel to the vertical direction. Specifically, in the above embodiment, the first connecting portion 128 is formed over the entire circumference of the single cell 110 in the first separator 120 in the vertical direction, but the first connecting portion is formed. If 128 is formed in at least a part of the first separator 120 around the single cell 110, the fuel cell stack 100 of the fuel cell stack 100 due to the difference in vertical displacement between the frames 130, 140 and the single cell 110. It is possible to suppress the deterioration of performance. For example, in the above embodiment, the first connecting portion 128 may be formed so as to be located at at least one of the first to fourth compartment regions E1 to E4. The first connecting portion 128 is preferably formed only in 50% or more of the entire circumference of the single cell 110 in the first separator 120, and is simply formed in the first separator 120. A configuration formed only in 80% or more of the entire circumference around the cell 110 is preferable. The same applies to the second connecting portion 188 of the second separator 180.

Further, in the above embodiment, the first connecting portion 128 has a curved shape so as to project toward the fuel chamber 176 side (lower side), but the first connecting portion 128 has an air chamber 166 side. It may have a curved shape so as to protrude (upper side). Further, in the above embodiment, the first connecting portions 128 formed on all the first separators 120 have a shape curved in the same direction (lower side), but are formed on some of the first separators 120. The formed first connecting portion 128 may have a shape curved in the direction opposite to that of the first connecting portion 128 formed on the other first separator 120 (upper side). However, as in the above embodiment, if the first connecting portion 128 formed on all the first separators 120 has a shape curved in the same direction, the end plates 104, 106 and the single cell 110 are in the vertical direction. Since all the first separators 120 are always uniformly deformed in the same direction with respect to the fluctuation of the displacement difference, it is possible to suppress a short circuit between the first separators 120. The depth of the recess of the first connecting portion 128 is preferably longer than the opening width of the recess (see FIG. 8). The same applies to the second connecting portion 188 of the second separator 180.

Further, in the above embodiment, the first separator 120 does not have to satisfy any of the above-mentioned first to third requirements, and is configured to satisfy at least one or two. You may. Further, the second separator 180 may be configured not to include the second connecting portion 188. Further, the second separator 180 may not satisfy any of the above-mentioned fourth to sixth requirements, and may be configured to satisfy at least one or two. Further, the second separator 180 may be configured not to include the second connecting portion 188.

Further, in the above embodiment, the number of single cells 110 included in the fuel cell stack 100 is only an example, and the number of single cells 110 is appropriately determined according to the output voltage and the like required for the fuel cell stack 100. Further, the material constituting each member in the above embodiment is merely an example, and each member may be composed of another material.

Further, in the above embodiment, the SOFC that generates power by utilizing the electrochemical reaction between hydrogen contained in the fuel gas and oxygen contained in the oxidizing agent gas is targeted, but the present invention relates to an electrolysis reaction of water. It is also applicable to an electrolytic single cell, which is a constituent unit of a solid oxide type electrolytic cell (SOEC) that uses it to generate hydrogen, and an electrolytic cell stack including a plurality of electrolytic single cells. The configuration of the electrolytic cell stack is not described in detail here because it is known, for example, as described in Japanese Patent Application Laid-Open No. 2016-81813, but is schematically the same as the fuel cell stack 100 in the above-described embodiment. It is the composition of. That is, the fuel cell stack 100 in the above-described embodiment may be read as an electrolytic cell stack, the power generation unit 102 may be read as an electrolytic cell unit, and the single cell 110 may be read as an electrolytic cell. However, during the operation of the electrolytic cell stack, a voltage is applied between both electrodes so that the air electrode 114 is positive (anode) and the fuel electrode 116 is negative (cathode), and the voltage is applied through the communication hole 108. Steam as a raw material gas is supplied. As a result, an electrolysis reaction of water occurs in each electrolytic cell unit, hydrogen gas is generated in the fuel chamber 176, and hydrogen is taken out to the outside of the electrolytic cell stack through the communication hole 108. Even in the electrolytic cell unit and the electrolytic cell stack having such a configuration, by forming the first connecting portion 128 on the first separator 120, the displacement difference between the end plates 104 and 106 and the single cell 110 in the vertical direction can be obtained. It is possible to suppress the deterioration of the performance of the fuel cell stack 100 due to this.

Further, in the above embodiment, the solid oxide fuel cell (SOFC) has been described as an example, but the present invention is used for other types of fuel cells (or electrolytic single cells) such as a molten carbonate fuel cell (MCFC). Is also applicable.

22: Bolt 24: Nut 26: Insulation sheet 27: Gas passage member 28: Main body 29: Branch 100: Fuel cell stack 100a: Fuel cell stack 102: Power generation unit 103: Cell block 104, 106: End plate 104A, 106A : Opening window 108: Communication hole 110: Single cell 112: Electrolyte layer 114: Air electrode 116: Fuel electrode 120, 120a: First separator 121: First separator through hole 122: First through hole peripheral portion 123: Cell side joint part 124: Joint part 126: First inner part 127: First outer part 128: First connection part 129: Frame side joint part 130: Air pole side frame 131: Air chamber hole 132: Oxidation Agent gas supply communication flow path 133: Oxidating agent gas discharge communication flow path 134: Air electrode side current collector 135: Current collector element 140: Fuel pole side frame 141: Fuel chamber hole 142: Fuel gas supply communication flow path 143 : Fuel gas discharge communication flow path 144: Fuel electrode side current collector 145: Electrode facing part 146: Interconnector facing part 147: Connecting part 149: Spacer 150: Interconnector 161: Oxidating agent gas introduction manifold 162: Oxidating agent gas discharging Manifold 166: Air chamber 171: Fuel gas introduction manifold 172: Fuel gas discharge manifold 176: Fuel chamber 180: Second separator 181: Second separator through hole 182: Second through hole peripheral part 183: Connector side joint 186: Second inner part 187: Second outer part 188: Second connecting part 189: Frame side joint part 190: Intermediate member B1: Shortest distance Δ B2: Shortest distance Δ C1: Length Δ C2: Length Δ E1 to E4: Sectional area FG: Fuel gas FOG: Fuel off gas OG: Oxidating agent gas OOG: Oxidating agent off gas

Claims (3)

A frame constituting a single cell including an electrolyte layer and an air electrode and a fuel electrode facing each other in a first direction across the electrolyte layer, and an air chamber facing the air electrode or a fuel chamber facing the fuel electrode. A frame member having a through hole and a separator through hole are formed, and a through hole peripheral portion surrounding the separator through hole is joined to the single cell and a peripheral edge portion is joined to the frame member to form an air chamber. An electrochemical reaction block in which a plurality of electrochemical reaction units including a separator for partitioning the fuel chamber are arranged side by side in the first direction,
A pair of end members located on both sides of the electrochemical reaction block in the first direction and arranged so that at least a part thereof overlaps the frame member in the first direction.
In an electrochemical reaction cell stack in which the pair of end members are fastened by a fastening member .
At least one of the pair of end members is formed with a space that opens to at least the electrochemical reaction block side and whose contour line includes the single cell in the first directional view.
At least one of the separators
The inner part including the peripheral part of the through hole and the inner part
The outer part located on the outer peripheral side from the inner part and
A connecting portion that connects the inner portion and the outer portion and projects to one side in the first direction with respect to both the inner portion and the outer portion.
Equipped with
In at least one cross section parallel to the first direction, the distance between the single cell joined to the at least one separator and the frame member in a third direction orthogonal to the first direction. The first distance is the distance between the cell-side joint portion joined to the single cell and the frame-side joint portion joined to the frame member in the at least one separator in the first direction. Is longer than the second distance,
It is characterized by an electrochemical reaction cell stack. In the electrochemical reaction cell stack according to claim 1 ,
In at least one cross section parallel to the first direction, the length of the connecting portion in the at least one separator is the cell-side joining portion joined to the single cell in the at least one separator. A third direction orthogonal to the first direction between the single cell joined to the at least one separator and the frame member from the shortest distance between the frame member and the frame-side joint. Longer than the length minus the first distance, which is the distance in the direction of
It is characterized by an electrochemical reaction cell stack. In the electrochemical reaction cell stack according to claim 1 or 2 .
In at least one cross section parallel to the first direction, among the at least one separator, a cell-side joint portion joined to the single cell and a frame-side joint portion joined to the frame member. The second distance, which is the distance in the first direction of the above, is larger than 0.01 mm.
It is characterized by an electrochemical reaction cell stack.

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